Improvement in escapements for time-keepers



2 Sheet-sSheet 1.

J. J. JOHNSTON. Esoa-pement for Time-Keepers.

Patented Oct. 21, 1879.

I] M #31. s g g .d TTORJVE XS 2 Sh:3ets-Sheet 2. J. J. JOHNSTON. Esoapement for Time-Keepers.

No. 220,763. Patented Oct. 21,1879.

INVENTOR A 90% gjwaz WW6. a m7(mc ATTORNEYJ UNITED STATES PATENT OEFIOE.

JOHN JAY JOHNSTON, OF PITTSFIELD, ILLINOIS.

IMPROVEMENT IN ESCAPEMENTS FOR TlME-KEEPERS.

Specification forming part of Letters Patent No. 220,763, dated October 21, 1879; application filed April '24, 1879. I

To all whom it may concern:

Be it known that I, JOHN JAY JOHNSTON, of Pittsfield, in the county of Pike and State of Illinois, have invented new and valuable ImprovementsiuTime-Keepers; and I do hereof the balance-wheel, showing the operating attachments. Figs. 4 and 5 are plan views of the escapement, showing the parts in different position. Figs. 6 and 7 are views of the bankin g device.

This invention relates to certain improvein ents in time-keepers; and the object is to provide improved means for regulating the motion of the escapement-wheel of the watch, and a banking device to prevent the balance-wheel under certain circumstances from vibrating beyond a certain point to destroy the regularity of motion to the movements.

My improvements consist in the novel construction of the oscillating pallet, the forked lever, and theattaclunents secured to the balance-wheel.

I My invention further consists in attaching an auxiliary spring to the balance-wheel-sup- .port frame, or in a continuation of the hairspring, in combination with a pin, forming a banking device, so arranged that as the hairspring uncoils it forces itself against the auxiliary spring, which prevents the balance-wheel from vibrating too far.

In the annexed drawings, forming a part of this specification, the letter A represents a portion. of one of the supporting-plates of a watch; B, the balancewheel, and O the scape or escapement wheel, of the usual construction substantially.

The letter D i ndieates the detent-lever, working on the pix 'ot I), located at an angle above the scape-wheel. To this lever is journaled, near its upper end, a device, 0, known as the detent-pallet, carrying a ruby, d, or other hard substance. This detent-pallet is so journaled to the detent-lever as to have a slight oscillatory movement, as shown by full lines in Figs. 4 and 5 of the drawings.

The rear or lower end of the detent-lever D is bifurcated or forked-that is to say, it has two arms, 0 f, of different lengths. The arm 0 has its outer end turned upward at right angles, as shown, to engage with the peripherical surface of the cam 11, and the short arm f engages with the pin 70, attached to the face of the cam i, and is moved by it far enough to disengage the detent-pallet from a tooth of scape-wheel.

The balance-wheel B is mounted upon the staff or shaft h, and has on its surface, in confact with the hub, a cam, 1', with pin 70, and an impulsearm, l, of the construction substantially as shownin Fig. 3 of the drawings.

The peripherical face of the cam '5 engages with the long arm 6 of the detent-lever, and secures the perfect lockin g of the escapement, and at the same time, owing to its construction, prevents the said lever from unlocking the scape-wheel.

' The pin 7. engages with the short arm f of the detent-lever, and moves it far enough to unlock the escapement, as shown in Fig. 5.

The impulse-arm 1 receives a tooth of the scape-wheel whenever the detent-pallet is re leased above, thereby causing the impulse stroke or movement to the balance-wheel. (See Fig. 5.) The balance-wheel in turning to the left, as shown by the arrow in Fig. 4, will bring the pin 7t in contact with the short arm f of the detent-lever, which will cause the parts to assume the position as indicated by dotted lines, and as soon as the pin L clears the said short arm the parts will resume their normal position. It will be seen that in this movement the balance-wheel has received no impulse-stroke; but on its returning to the right, as indicated by arrow in Fig. 5, the pin 7; will come in contact with the short arm of lever again, and carry it around with it far enough to cause the parts to assume the position as seen in Fig. 5, which will unlock the tooth H of the scape-wheel. Now, as the scape-wheel is free the tooth I will encounter the impulse-arm l, and forceit around with it,

thereby causing the balance-wheel to vibrate. The tooth H in advancing will encounter the lift at of the detent-pallet, and set the pallet in position to receive the following tooth of the scape-wheel. The spring at, secured to post 1), controls the fall of the detent-lever, and-retains it at the proper inclination to receive the pin in the cam t.

The escapement can only be unlocked by the detent-lever being moved in the direction of the arrow 2, and the lever is prevented from moving in this direction at the wrong time by the lon g arm 0, guarded by the cam 1'. \Vhen the proper time arrives for unlocking, the notch in the camt' presents itself in front of the long arm 0 just as the pin it encounters the short arm, the bent portion of the arm passinginto the notch, and is thus thrown back into position by the tooth of scape-wheel coming in contact with the lift.

The letter It represents the balance-wheel of the time-piece, and is actuated by the es eapementwheel and the hair-spring s.

The auxiliary or outer spring, I, forming a part of the banking device, is pinned to the hair-sprin stud a, and the other or free end is bent as shown, to engage with the pin v, fixed to the balance-bridge. One of the arms of the balancewheel is provided with a pin, a, near its rim, for the purpose hereinafter stated.

The balance-wheel in turning in the direction as indicated by the arrow causes the hairspring to expand, which in return forces the spring t outwardly and the bent end in front of the pin 12. The pin 20 then comes in contact with the outer surface of the said spring I, at which point the vibration of the balance is stopped in that direction, thereby preventing the escapement from being unlocked out of regular order. Fig. 7 is a modification of the banking device, and works substantially in the SZLHIG 11121-111161.

hat I claim as my invention, and desire. to secure by Letters Patent, is-

1. A detent-lever, D, having at its lower or rear end the bifurcated arms 0 f, the outer end of the arm 6 being bent at right angles to its body, substantially as shown and described.

2. The detent-lever D, having at its lower or rear end the arms 0 f, of the construction substantially as described, in combination with the cam t and the pin 70, attached to the face of the cam, substantially as described, and for the purpose set forth.

8. The combination, with the scape-wheel, of the balance-wheel provided with the operatin g devices, the detentlevcr, the oscillating detent-pallet, and the spring 01 substantially as and for the purposes set forth.

4. A balance-wheel having a pin to engage with the expanded portion of the spring to limit the vibration of the balance, substantially as described.

5. In combinationwith the balancewheel having the pin 10, the auxiliary spring I for limiting the vibration of the balance-wheel, substantially as described.

In testimony whereof I have hereunto subscribed my name.

JOHN JAY JOHNSTON.

Vitnesses T. I. OoULrAs, JNo. L. FIELD. 

